The present invention relates to chemical compounds that inhibit Mps-1 (Monopolar Spindle 1) kinase (also known as Tyrosine Threonine Kinase, UK). Mps-1 is a dual specificity Ser/Thr kinase which plays a key role in the activation of the mitotic checkpoint (also known as spindle checkpoint, spindle assembly checkpoint) thereby ensuring proper chromosome segregation during mitosis [Abrieu A et al., Cell, 2001, 106, 83-93]. Every dividing cell has to ensure equal separation of the replicated chromosomes into the two daughter cells. Upon entry into mitosis, chromosomes are attached at their kinetochores to the microtubules of the spindle apparatus. The mitotic checkpoint is a surveillance mechanism that is active as long as unattached kinetochores are present and prevents mitotic cells from entering anaphase and thereby completing cell division with unattached chromosomes [Suijkerbuijk S J and Kops G J, Biochemica et Biophysica Acta, 2008, 1786, 24-31; Musacchio A and Salmon E D, Nat Rev Mol Cell Biol., 2007, 8, 379-93]. Once all kinetochores are attached in a correct amphitelic, i.e. bipolar, fashion with the mitotic spindle, the checkpoint is satisfied and the cell enters anaphase and proceeds through mitosis. The mitotic checkpoint consists of a complex network of a number of essential proteins, including members of the MAD (mitotic arrest deficient, MAD 1-3) and Bub (Budding uninhibited by benzimidazole, Bub 1-3) families, the motor protein CENP-E, Mps-1 kinase as well as other components, many of these being over-expressed in proliferating cells (e.g. cancer cells) and tissues [Yuan B et al., Clinical Cancer Research, 2006, 12, 405-10]. The essential role of Mps-1 kinase activity in mitotic checkpoint signalling has been shown by shRNA-silencing, chemical genetics as well as chemical inhibitors of Mps-1 kinase [Jelluma N et al., PLos ONE, 2008, 3, e2415; Jones M H et al., Current Biology, 2005, 15, 160-65; Dorer R K et al., Current Biology, 2005, 15, 1070-76; Schmidt M et al., EMBO Reports, 2005, 6, 866-72].
There is ample evidence linking reduced but incomplete mitotic checkpoint function with aneuploidy and tumorigenesis [Weaver B A and Cleveland D W, Cancer Research, 2007, 67, 10103-5; King R W, Biochimica et Biophysica Acta, 2008, 1786, 4-14]. In contrast, complete inhibition of the mitotic checkpoint has been recognised to result in severe chromosome missegregation and induction of apoptosis in tumour cells [Kops G J et al., Nature Reviews Cancer, 2005, 5, 773-85; Schmidt M and Medema R H, Cell Cycle, 2006, 5, 159-63; Schmidt M and Bastians H, Drug Resistance Updates, 2007, 10, 162-81].
Therefore, mitotic checkpoint abrogation through pharmacological inhibition of Mps-1 kinase or other components of the mitotic checkpoint represents a new approach for the treatment of proliferative disorders including solid tumours such as carcinomas and sarcomas and leukaemias and lymphoid malignancies or other disorders associated with uncontrolled cellular proliferation.
Different compounds have been disclosed in prior art which show an inhibitory effect on Mps-1 kinase:
WO 2009/024824 A1 discloses 2-Anilinopurin-8-ones as inhibitors of Mps-1 for the treatment of proliferate disorders. WO 2010/124826 A1 discloses substituted imidazoquinoxaline compounds as inhibitors of Mps-1 kinase. WO 2011/026579 A1 discloses substituted aminoquinoxalines as Mps-1 inhibitors.
Substituted triazolopyridine compounds have been disclosed for the treatment or prophylaxis of different diseases:
WO 2008/025821 A1 (Cellzome (UK) Ltd) relates to triazole derivatives as kinase inhibitors, especially inhibitors of ITK or PI3K, for the treatment or prophylaxis of immunological, inflammatory or allergic disorders. Said triazole derivatives are exemplified as possessing an amide, urea or aliphatic amine substituent in position 2.
WO 2009/047514 A1 (Cancer Research Technology Limited) relates to [1,2,4]-triazolo-[1,5-a]-pyridine and [1,2,4]-triazolo-[1,5-c]-pyrimidine compounds which inhibit AXL receptor tyrosine kinase function, and to the treatment of diseases and conditions that are mediated by AXL receptor tyrosine kinase, that are ameliorated by the inhibition of AXL receptor tyrosine kinase function etc., including proliferative conditions such as cancer, etc. Said compounds are exemplified as possessing a substituent in the 5-position and a substituent in the 2-position.
WO 2009/010530 A1 discloses bicyclic heterorayl compounds and their use as phosphatidylinositol (PI) 3-kinase. Among other compounds also substituted triazolopyridines are mentioned.
WO 2009/027283 A1 discloses triazolopyridine compounds and their use as ASK (apoptosis signal-regulating kinase) inhibitors for the treatment of autoimmune diseases and neurodegenerative diseases.
WO 2010/092041 A1 (Fovea Pharmaceuticals SA) relates to [1,2,4]-triazolo-[1,5-a]-pyridines, which are said to be useful as selective kinase inhibitors, to methods for producing such compounds and methods for treating or ameliorating kinase-mediated disorder. Said triazole derivatives are exemplified as possessing a 2-chloro-5-hydroxyphenyl substituent in the 6-position of the [1,2,4]-triazolo-[1,5-a]-pyridine.
WO 2011/064328 A1, WO 2011/063907 A1, WO 2011/063908 A1, WO 2012/143329 A1 and WO 2013/087579 A1 relate to [1,2,4]-triazolo-[1,5-a]-pyridines and their use for inhibition of Mps-1 kinase.
However, the state of the art described above does not specifically disclose the substituted triazolopyridine compounds of general formula (I) of the present invention, or a tautomer, an N-oxide, a hydrate, a solvate, or a salt thereof, or a mixture of same, as described and defined herein, and as hereinafter referred to as “compounds of the present invention”, or their pharmacological activity.